Exhaust purification devices for purifying exhaust gas discharged from an internal combustion engine by collecting PM contained in the exhaust gas by means of a filter are known. As the exhaust purification devices, a device is also known in which PM sensors are respectively arranged upstream and downstream of a filter in an exhaust direction, so that it is possible to determine whether or not the filter has a failure. For example, in an exhaust purification device described in Patent Reference 1, resistance-type PM sensors, which can be regenerated by a heater, are respectively arranged upstream and downstream of a filter in an exhaust direction. An inflow PM amount to be introduced into the filter and an outflow PM amount discharged from the filter are acquired based on detection signals from the respective PM sensors, and also a collecting efficiency is obtained therefrom. Then, whether or not the filter has a failure is determined by comparing the collecting efficiency with a predetermined determination threshold.